Contrarotation propeller



July 15, 1947. c, ANDERsON 2,424,135

CONTRA ROTATION PROPELLER Filed Oct. 21, 1944 2 Sheets-Sheet 1 July 15, 1947.

H. C. ANDERSON CONTRA ROTATION PROPELLER 2 Sheets-Sheet 2 Filed Oct. 21, 1944 flaroZczGdZrzdersow Patented July 15, 1947 UNITED STATES PATENT OFFICE CONTRAROTATION PROPELLER.

Harold C. Anderson, Chicago, 111.

Application October 21 1944, Serial No. 559,712

6 Claims.

The invention relates to contr'arotation propellers.

The primary object of the invention is to improve the aerodynamic efiiciency of contrarotational propellers.

From experiments I have found that the aerodynamic efiiciency or thrust coefficient of contrarotational propellers will be improved by providing the blades of the propellers having wings or extensions with intermediate spaces through which the wings are adapted to pass in the rotation of the propellers in opposite directions. This result is believed to result from causing the air to be advantageously deflected by the blades provided with the wings so that the blades. in their opposite rotation will impart the air so that a greater portion thereof will be deflected from rotative to backward movement and the blades will more effectively attack the air stream to produce a greater static thrust than that which results from propellers with blades of conventional :airfoil contour. achieving greater static thrust the leading portion of the forward propeller of the blades ex-v tends substantially continuously from the hub to the tip and the trailing portion is provided with wings or extensions, the blades of the rear propeller are provided with continuously extending trailing sections and wings or extensions in their leading portions and with intermediate spaces, and the wings or extensions on the blades of the forward propeller rotate through the spaces and between the wings on the rear propeller and the rear propeller through the spaces between the wings on the front propeller.

The invention consists in the several novel features hereinafter set forth and more particularlydefined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a front elevation of a contrarotation propeller.

Fig. 2 is a side elevation.

Fig. 3 is a section taken on line 33 of Fig. 1, illustrating the front and rear oppositely rotating blades in a position assumed while the wings on each of the blades are passing through the spaces between the wings on the other blade.

Fig. 4 is a section similar to Fig. 3, illustrating the relative position of the blades in a position assumed while the oppositely rotating blades are not in crossed or overlapping relation.

Fig. 5 is a section taken on line 55 of Fig. 1.

Fig. 6 is a section taken on line 6-5 of Fig. 2.

The invention is exemplified in contrarotation propellers which comprisea forward pro= In these propellers for peller 8 which includes a pair of propeller blades prises a leading section or member M which extends continuously from the hub to the tip of the blade and is provided with a continuous leading edge t5 and a series of wings or extensions I6 which are disposed. along the trailing portion of said blade and are radially separated from one another by notches IT. The continuous section Id of each blade It is provided with a thrust face [8 having suitable pitch angle and the wings l6 have a thrust face [9 of predetermined lesser pitch angle extending rearwardly from the thrust face IS .on thecontinuous section 14 to the trailing edge of the wings. The continuous section M has a suction face 2!} of airfoilcrossesectional contour between the continuous leading edge I5 and the trailing edge, 2! of the.continuous blade section 14 between the section It or at the. front of notches ll. The wings N5 of each blade ID are provided with suction faces 22'of airfoil cone tour which extend from their trailing edges 23 to the portion of greatest thickness of the continuous section M of the blade. The leading edge l5 of thecontinuous section l4 and the portion of said section between the longitudinal axis of the blade I0 and the leading edge may be of conventional airfoil profile. The portion of the continuous section l4 betweenthe leading edge portions 2| and the longitudinal axis of blade II] is of lesser width than the portion between said axis and the leading edge [5. The wings l6 are extended rearwardly from thelongitudinsal axis of the blade H} or are of sufiicient width so that the longitudinal continuous portion on one side of the longitudinal axis of the blade will have the same weight as the wings and the continuous portion of the blade on the opposite side of said longitudinal axis, so that the blade will be-substantially balanced statically on its longitudinal axis.

Each blade it of the rear propeller 9 comprises a' trailing section or member 26 which extends continuously from the hub to the tip of the blade 21 and a series of wings'or extensions ZS-whicharedisposed along the leading'portionof said 3 blade and are radially separated from one another by spaces or notches 29. The continuous section 26 of each blade l2 has a continuous thrust face 30 of suitable pitch angle for the trailing section of blade l2 and the wings 23 have a thrust face 3| extending forwardly from the leading edge portion 32 or at the notches 29 to the leading edges 33 of the wings 28. The continuous section 26 has a suction face 34 between the leading edge portion 32 and the trailing edge 21 of a predetermined pitch. The wings 28 are provided with suction face portions 35 of lesser pitch extending between the leading edge portions 33 of the wings and the suction faces 34 on the continuous section 26. The trailing edge 21 of the continuous section 26 and the portion of said section between the longitudinal axis of the blade 12 and the trailing edge 2'! may be of conventional airfoil profile. The portion of the continuous section 26 between its leading edge portions 32 and the longitudinal axis is of lesser width than the portion between said aXis and the trailing edge 21 of blade l2. The wings 23 are extended from said longitudinal axis or a sufficient distance therefrom so that the portion of the blade provided with wings and notches will be suitably balanced statically on said axis. The wings I6 on the forward blades l0 are radially positioned to rotate through the notches 28 in the rear blades l 2 and the wings 28 on the rear blade are adapted to rotate through the notches l1 in the forward blades so that the wings on the oppositely rotating propellers will overlap in their plane of rotation and the blades of each propeller will rotate with clearance through the notches in the .blades of the oppositely rotating propeller.

In this construction, the improved thrust coefficient is believed to be caused by the airflow produced in counterdirections to the rotation of the blades by the suction around the edges of the wings and in the spaces between them. The suction produced around the outer edges of the wings and in the spaces between them reduces the rotative movement of the air by the thrust face on the blade on each of the propellers so that the wings on the oppositely rotating propellers will strike at least some counterflow air at such an angleof incidence that the thrust faces of said other propeller will deflect the air more nearly in a rearward direction. In this operation, it has been found that for greater aerodynamic efficiency, the pitch of the thrust faces on the wings should be somewhat less than the pitch of the thrust faces of the continuous sections of the blades which may be of the usual pitch angle of the conventional propeller. The blades may be longitudinally twisted from the hub to the tip in accordance with the formula for conventional propeller blades.

The invention may be used in propellers for different uses, such as airplanes or helicopters, and in propellers with any suitable number of blades.

The invention is not to be understood as restricted to the details set forth, since these may be modified within the scope of the appended claims without departing from the spirit and scope of the invention.

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

1. Contrarotational coaxial propellers, each comprising blades with longitudinally continuous sections along one of their edgesand wings spaced apart radially along and projecting from its opposite edge, the wings on each propeller being positioned to rotate through the spaces between the wings on the other propeller.

2. Contrarotational coaxial propellers each comprising blades with longitudinally continuous sections along one of their edges and wings spaced apart radially along and projecting from its opposite edge, the wings on each propeller being positioned to rotate through the spaces between the wings on the other propeller, the continuous section and the wings of each propeller having thrust faces of different pitch.

3. Contrarotational coaxial propellers each comprising blades with longitudinally continuous sections along one of their edges and wings spaced apart radiall along and projecting from its onposite edge, the wings on each propeller being positioned to rotate through the spaces between the wings on the other propeller, the continuous section having thrust faces of a predetermined pitch and the wings having thrust faces of a lesser pitch.

4. Contrarotational coaxial propellers comprising:' a forward propeller provided with a longitudinally continuous leading edge section and wings projecting from and spaced apart radially along the trailing portion of the continuous section; and a rear propeller provided with a longitudinally continuous trailing portion and wings projecting from and spaced apart radially along the leading edge of said continuously extending trailing portion; the wings of each propeller being disposed to rotate through the spaces between the wings of the other propeller.

5. Contrarotational coaxial propellers comprising: a forward propeller provided with a longitudinally continuous leading edge section and wings projecting from and spaced apart radially along the trailing portion of the continuous sec-. tion; and a rear propeller provided with a longitudinally continuous trailing portion and wings projecting from and spaced apart radially along the leading edge of said continuously extending trailing portion, the wings of each propeller being disposed to rotate through the spaces between the wings of the other propeller; each propeller having its continuous section and its wings provided with thrust faces.

6. Contrarotational coaxial propellers comprising: a forward propeller provided with a longitudinally continuous leading edge section and wings projecting from nd spaced apart radially along the trailing portion of the continuous section; and a rear propeller provided with a longitudinally continuous trailing portion and wings projecting from and spaced apart radially along the leading edge of said'continuously extending trailing portion, the wings of each propeller being disposed to, rotate through the spaces between the win s of the other propeller; each propeller having its continuous section provided with a thrust face of a predetermined pitch and its wings provided with thrust faces of a lesser pitch,

HAROLD c. ANDERSON.

REFERENCES CITED The following references file of this patent:

are of record in the Number Date I 2,313, 24 Caldwell Mar. 2 i943 

